I'm not sure I understand the full impact of the unloader on my pressure washer. I was able to reduce the pressure at my wand tip by adjusting the unloader for doing a fence and it worked fine. I assume that the rate of flow was not changed and it still delivered 4 gpm at the reduced pressure. I also have a surface scrubber that I plan to use on a pool deck for cleaning. Not wanting to damage the surface with too high a pressure (I have a 3500 psi, 13 hp Honda with a two tip spinner) I would like to use the unloader to lower the pressure to my scrubber. Is this likely to cause a problem with the equipment? Will the scrubber be damaged or ineffective? I am not sure I understand what impact the unloader has on the pump either. Does it cause additional strain and premature wear? I'm sure there are alternative and better ways to get the same desired result, but this job is coming up in the next few days and I would like to get the best results with the equipment I currently have. Thanks for your input!
Unloader Help Needed
- Thread starter jerryb
- Start date
What's purpose of unloader?
Thanks Mr Alan for your reply. If not for adjusting pressure, then what is the unloader placed on the equipment for? I guess it's kind of like an appendix to me now since I don't know what use it has. Can anyone explain to me why a pressure adjusting unloader is placed on my pressure washer? I used a wide angle tip when I adjusted the pressure to do my fence.
Thanks Mr Alan for your reply. If not for adjusting pressure, then what is the unloader placed on the equipment for? I guess it's kind of like an appendix to me now since I don't know what use it has. Can anyone explain to me why a pressure adjusting unloader is placed on my pressure washer? I used a wide angle tip when I adjusted the pressure to do my fence.
It's similar to a relief valve...Your pump always puts out the same amount of water. (I think they call it constant velocity.) When you release the gun trigger that water has no place to go. The unloader "unloads" and gives it an escape route.
My recommendation is... once you've set the unloader, NEVER touch it again.
My recommendation is... once you've set the unloader, NEVER touch it again.
You can use your regulator the reduce flow rate (GPM).
Your regulator (unloader) can be used to adjust the flow rate (GPM) and pressure (PSI). Both will be affected at the same time. However, you will not know what PSI and GPM's you are getting. With even a good liquid filled pressure gauge, your readings may not be accurate (for PSI). To measure your GPM's, you would have to time and collect your spray in a container.
The easiest way to know your PSI at the nozzle, is to leave your regulator fully open and that will give you your rated GPM/PSI within +/- 5% (when equipment is new). By changing your nozzle size (going from a 4.0 to a 6.0), you maintain your flow rate (GPM) but will reduce your pressure (PSI). Theoretically, changing nozzle angles will not change your PSI or GPM. I'm not sure where PSI is theoretically calculated on nozzles (it could be at the exit of the nozzle or at a distance of 1 inch from the tip). Normal ratings are calculated at the change of orifice size, which would be on the inside of the nozzle. As you move your nozzle further away from your work surface the pressure will change at the contact point but not at the nozzle.
Regards,
Your regulator (unloader) can be used to adjust the flow rate (GPM) and pressure (PSI). Both will be affected at the same time. However, you will not know what PSI and GPM's you are getting. With even a good liquid filled pressure gauge, your readings may not be accurate (for PSI). To measure your GPM's, you would have to time and collect your spray in a container.
The easiest way to know your PSI at the nozzle, is to leave your regulator fully open and that will give you your rated GPM/PSI within +/- 5% (when equipment is new). By changing your nozzle size (going from a 4.0 to a 6.0), you maintain your flow rate (GPM) but will reduce your pressure (PSI). Theoretically, changing nozzle angles will not change your PSI or GPM. I'm not sure where PSI is theoretically calculated on nozzles (it could be at the exit of the nozzle or at a distance of 1 inch from the tip). Normal ratings are calculated at the change of orifice size, which would be on the inside of the nozzle. As you move your nozzle further away from your work surface the pressure will change at the contact point but not at the nozzle.
Regards,
Michael
New member
It is not a relief valve but an integral safety device for the prevention of over pressure situations.
When a trigger gun is released there is a short pressure spike that causes the springs in the unloader to reduce pressure on the pump head. In doing so the spring releases pressure on the head and allows water to bypass, usually in a short loop to allow the pump to continue pumping for a short time only. As the loop is very short the water will heat up quite quickly due to friction from pumping and eventually cause a seal failure leading to oil in the crankcase and a potentially expensive repair.
As it is a primary safety device it is set at the factory for the specifications of the pump and should never be adjusted. There are springs and o-rings that wear so adjustment will accelerate the wear.
Pumps are all positive displacement. By that I mean that depending on pump RPM it will put out the same amount of water every time. All the tip does is put a restriction in the end of the system that provides the pressure; just like putting your thumb over the end of a garden hose. Tips are sized according to the orifice number. Check out
http://www.arnorthamerica.com/spraynozzlechart.html
for an excellent one. It is simple to use, find the closest flow to the rating of your pump in the body. The left hand column is the number size of the tip and the top row is the pressure that size orifice will create. NEVER, EVER over pressure your machine. Extreme damage will result. Tips are designed to work most effectively at 6-12" from the surface to be cleaned. A 0 tip will give you concentrated force and is highly dangerous and should only be used with great care. 15 and 25 degree tips are most common as they strike a balance between coverage and power. A 40 degree tip is best used for rinsing as the power disipates rapidly. You can also adjust the pressure by moving the tip away from the work. FYI, typically a coin-op car wash will use 1200 PSI and a 40 degree tip to use as a comparison.
There are also two basic types of unloaders: hard and soft.
Hard unloaders trap pressure in the line so the hose is fairly stiff and can be difficult to drag around. They are cost effective and tend to be more durable and forgiving.
Soft unloaders allow for a soft hose because they relieve trapped pressure. They are usually more expensive and tend not to be as durable.
Personal preferences dictate which one you use.
Simply put, adjust pressure by changing tips. Never adjust the unloader as it is a primary safety device.
Hope this helps? Cheers.
When a trigger gun is released there is a short pressure spike that causes the springs in the unloader to reduce pressure on the pump head. In doing so the spring releases pressure on the head and allows water to bypass, usually in a short loop to allow the pump to continue pumping for a short time only. As the loop is very short the water will heat up quite quickly due to friction from pumping and eventually cause a seal failure leading to oil in the crankcase and a potentially expensive repair.
As it is a primary safety device it is set at the factory for the specifications of the pump and should never be adjusted. There are springs and o-rings that wear so adjustment will accelerate the wear.
Pumps are all positive displacement. By that I mean that depending on pump RPM it will put out the same amount of water every time. All the tip does is put a restriction in the end of the system that provides the pressure; just like putting your thumb over the end of a garden hose. Tips are sized according to the orifice number. Check out
http://www.arnorthamerica.com/spraynozzlechart.html
for an excellent one. It is simple to use, find the closest flow to the rating of your pump in the body. The left hand column is the number size of the tip and the top row is the pressure that size orifice will create. NEVER, EVER over pressure your machine. Extreme damage will result. Tips are designed to work most effectively at 6-12" from the surface to be cleaned. A 0 tip will give you concentrated force and is highly dangerous and should only be used with great care. 15 and 25 degree tips are most common as they strike a balance between coverage and power. A 40 degree tip is best used for rinsing as the power disipates rapidly. You can also adjust the pressure by moving the tip away from the work. FYI, typically a coin-op car wash will use 1200 PSI and a 40 degree tip to use as a comparison.
There are also two basic types of unloaders: hard and soft.
Hard unloaders trap pressure in the line so the hose is fairly stiff and can be difficult to drag around. They are cost effective and tend to be more durable and forgiving.
Soft unloaders allow for a soft hose because they relieve trapped pressure. They are usually more expensive and tend not to be as durable.
Personal preferences dictate which one you use.
Simply put, adjust pressure by changing tips. Never adjust the unloader as it is a primary safety device.
Hope this helps? Cheers.
M.Hinderliter
New member
The unloader gives you the ability to use a trigger gun. When you let off on the trigger the water has no where to go and if not for the unloader then something would rupture, usually a hose. But I have also seen pump heads severly damage because the unloader failed.
When the trigger is closed then the unloader is in the bypass mode. This mean the pump is still pumping and the water is being diverted away from the flow going to the pressure gun. Normally, this means the water flow is just being circulated back into the water supply of the pump (recirculated). Allowing the pump to remain in the bypass mode for extended periods of time can over heat the packing. Meaning that a pressure loss can be experience due to premature packing failure. We usually train our guys not to let the pump stay in bypass mode over 2 minutes. This can be extended depending on how the pump is plumbed.
All this explanation is a build up to your question about regulating pressure with the unloader. If you turn down the unloader to reduce the pressuer then you also turn down the flow. This can cause excessive wear on the unloader. It can possible cause the pump to over heat quicker in the bypass mode, not likely though. But more importantly, this is a safety issue, if you are running a hot water machine the flow of water going through the heater will get over heated. The over heating occurs because heaters heat based on flow. The water can even turn into steam causing a rupture. There are devices on the market that can help prevent this though.
To keep it simple and safe, just regulate your pressure by chaning nozzle sizes.
When the trigger is closed then the unloader is in the bypass mode. This mean the pump is still pumping and the water is being diverted away from the flow going to the pressure gun. Normally, this means the water flow is just being circulated back into the water supply of the pump (recirculated). Allowing the pump to remain in the bypass mode for extended periods of time can over heat the packing. Meaning that a pressure loss can be experience due to premature packing failure. We usually train our guys not to let the pump stay in bypass mode over 2 minutes. This can be extended depending on how the pump is plumbed.
All this explanation is a build up to your question about regulating pressure with the unloader. If you turn down the unloader to reduce the pressuer then you also turn down the flow. This can cause excessive wear on the unloader. It can possible cause the pump to over heat quicker in the bypass mode, not likely though. But more importantly, this is a safety issue, if you are running a hot water machine the flow of water going through the heater will get over heated. The over heating occurs because heaters heat based on flow. The water can even turn into steam causing a rupture. There are devices on the market that can help prevent this though.
To keep it simple and safe, just regulate your pressure by chaning nozzle sizes.
Thanks for the education!
Just a word of thanks to all who answered my post. Unfortunately the owner of the company where I bought my equipment suggested the unloader adjusting method for reducing the psi. I ran the pressure washer for a couple of hours with the unloader adjusted down to do a fence. I feel a littler better informed now, however, on how to select and use tip sizes as a recommended method for pressure adjusting. Thanks again and please if anyone else has comments to add please do so - I'm still learning. Also, would a HiLo tip be another answer to my dilemna? What about a dual lance? I'm not completely sure how these two items might fit in the bag of tricks.
Just a word of thanks to all who answered my post. Unfortunately the owner of the company where I bought my equipment suggested the unloader adjusting method for reducing the psi. I ran the pressure washer for a couple of hours with the unloader adjusted down to do a fence. I feel a littler better informed now, however, on how to select and use tip sizes as a recommended method for pressure adjusting. Thanks again and please if anyone else has comments to add please do so - I'm still learning. Also, would a HiLo tip be another answer to my dilemna? What about a dual lance? I'm not completely sure how these two items might fit in the bag of tricks.
midstateclean
New member
jerry,
new to pressure cleaning also, i've talked to alot of different people regarding some of the same issues today. They all pretty much said the same thing ,"leave the unloader alone, it is factory preset and essentially should not be changed, use different tips."
I had thought the same as you, but I am learning ALOT here too.
Just bought a surface cleaner from these guys down in your neck of the woods, ever had any dealings with them ? http://www.pressurewasherstore.com
Mark Thornsberry
MidState Cleaning
new to pressure cleaning also, i've talked to alot of different people regarding some of the same issues today. They all pretty much said the same thing ,"leave the unloader alone, it is factory preset and essentially should not be changed, use different tips."
I had thought the same as you, but I am learning ALOT here too.
Just bought a surface cleaner from these guys down in your neck of the woods, ever had any dealings with them ? http://www.pressurewasherstore.com
Mark Thornsberry
MidState Cleaning
jerry
my 2 cent's worth is that your right on the money with the DUEL LANCE. On top of reg. pressure it also allows you to draw your chem from the downstreamer without returning to the PW.
Also say your wanding a small area on cement-that is rinseing after your surface cleaner- on one side of the duel lance you have the wide spray for rinseing and a 15 deg on the other for getting a little left over gum or the corners.
It's a real handy tool.
my 2 cent's worth is that your right on the money with the DUEL LANCE. On top of reg. pressure it also allows you to draw your chem from the downstreamer without returning to the PW.
Also say your wanding a small area on cement-that is rinseing after your surface cleaner- on one side of the duel lance you have the wide spray for rinseing and a 15 deg on the other for getting a little left over gum or the corners.
It's a real handy tool.
Steven Rowlett
Member
Nozzle Chart
We have added a nozzle chart to our website this week www.rowlettpressure.com and can be printed from the site. Find the gpm of your machine and highlight it across and you will know which nozzle will deliver the pressure needed for the job you are doing. A rollover nozzle is also a quick way to go from one nozzle size to another.
We have added a nozzle chart to our website this week www.rowlettpressure.com and can be printed from the site. Find the gpm of your machine and highlight it across and you will know which nozzle will deliver the pressure needed for the job you are doing. A rollover nozzle is also a quick way to go from one nozzle size to another.
gREAT cHART mIKE